U.S. Pat. No. 2,761,111 discloses a known breakaway electrical connector for terminating an electrical cable. The electrical connector is arranged to be mechanically engagable with a mating electrical connector to provide an electrically conductive path from the electrical cable to the mating connector. The connectors can be firmly engaged but quickly and easily disengaged when required.
The mating electrical connector described in the US patent is a female connector having a receptacle within which is formed an annular groove. An endless coil spring is retained within the annular groove and partially protrudes therefrom. A plurality of elongate contacts is also arranged within the receptacle and maintained in a parallel longitudinal configuration by a dielectric spacing element.
The cable-terminating connector described in the US patent is a male connector in the form of a plug. A rearward end of the plug is provided with an opening for routing the cable away from the connector in a longitudinal direction. A forward end portion of the plug is provided with an annular groove which is shaped and dimensioned to receive the protruding part of the endless coil spring when the plug and the receptacle of the mating connector are engaged. A plurality of elongate sprung contacts is also arranged within the plug and maintained in a parallel longitudinal configuration by a dielectric spacing element.
The forward tip of the plug is tapered to exert a cam action, whereby an inward thrust of the plug into the receptacle of the mating connector will expand the coil spring to enable the spring to snap into the annular groove formed in the plug, and thus maintain the engagement of the connectors. In this way the sprung contacts of the plug may be held in firm pressure engagement with the fixed contacts of the receptacle to provide the electrically conductive path. The connectors are disengaged by exerting a longitudinal or transverse force on the plug or the cable to thereby expand the coil spring to enable the spring to snap out of the annular groove formed in the plug.
A problem associated with the known breakaway connector arrangement disclosed in U.S. Pat. No. 2,761,111 is that tension on the electrical cable can lead to accidental disengagement of the connectors. Furthermore, tension applied on the cable for deliberately disengaging the connectors may cause excessive stress on the connections and lead to damage.
GB 2 477 987 discloses an angled electrical connector for terminating an electrical cable and for engaging with a mating electrical connector. The angled connector comprises a body having an engagement portion including a sleeve which extends in a longitudinal first direction for engaging with the mating electrical connector, the body further having an opening for routing conductors of the cable away from the connector. At least one resilient member is arranged on the sleeve of the engagement portion, the resilient member being capable of deforming in a transverse direction perpendicular to the first direction and providing a reaction force for maintaining the engagement of the connector with the mating connector.
The opening of the body for routing the conductors of the cable away from the connector is arranged to route the cable in a second direction substantially perpendicular to the first direction. The resilient member comprises a coil spring extending about the sleeve of the engagement portion, the coils of the coil spring having a canted arrangement.
In this design, tension on the cable is less likely to lead to accidental disengagement with a mating electrical connector. In particular, the tension on the cable is in a direction which is substantially perpendicular to the direction of a force required for disengaging the connectors. Furthermore, when the mating connector is mounted in a panel, the connectors may be conveniently disengaged by inserting a user's hand between the panel and the cable to pivoting the cable away from the panel.
Such ‘breakaway’ connectors have a further advantage in that the pushing on and pulling off of the connector provides a significant tactile feedback to the operator that the connector has made a good contact, even when the operator is operating in poor environmental conditions which require protective clothing. For example in cold and freezing conditions thick gloves are needed to be worn which would dull the tactile experience. However such breakaway connectors as shown in U.S. Pat. No. 2,761,111 and GB 2477987 generally have a problem in that a sufficient applied force or force applied in a specific direction, such as an accidental collision, may disengage the cable and connector.
In this context, there is a need for a design which maintains the advantages of breakaway connectors but that accidental disengagement is prevented not only by a pivoting action.